U.S. Pat. Nos. 4,497,196 and 4,819,476, both of which are incorporated herein by reference, disclose a stamping and forming machine having first and second ram assemblies which are reciprocable toward and away from each other along horizontal paths of reciprocation. Strip material is fed along a strip feed path which extends between the ram assemblies. The ram assemblies have tooling on their ends for performing stamping and forming operations on the strip. The ram assemblies are reciprocated by oscillating levers to which the are coupled. The levers, in turn, are coupled to a central power shaft by eccentric assemblies. One example of typical punch and die tooling for use in a stamping and forming machine is disclosed in U.S. Pat. No. 5,007,282, which is incorporated herein by reference.
Another typical tooling assembly 10, as disclosed in the '476 patent, is shown in FIG. 1. Note that the view in FIG. 1 is an end-view with the direction of reciprocation being perpendicular to the paper. The tooling assembly 10 includes a base plate 12, two side plates 14 and 16, and a removable cover plate 18. The two side plates 14 and 16 are attached to the base plate 12 by means of screws 20 to form a rigid U-shaped member. The top outer edges of the two side plates have rabbets 22 and 24 formed therein. The cover plate 18 has a pair of flanges 26 and 28 extending from is downwardly facing surface 30 that straddle the two side plates and are in slip fit engagement with the walls of the rabbets 22 and 24. The inner walls of the U-shaped member and the surface 30 form a passageway within which the punch and die assemblies reciprocate. A punch ram 32, which is moved by an oscillating lever 34 as described above, is shown in the passageway. The cover plate 18 is secured in place by means of the knurled head screws 36, which are threaded into the two side plates 14 and 16. When it is desired to access the punch and die assemblies for sharpening or for other reasons, the screws 36 and the cover plate 18 are removed. Since the punch and die assemblies are in sliding contact with the surface 30 of the cover and there is a film of lubricant between the surfaces, atmospheric pressure prevents the easy separation of the cover from the punch and die assemblies. The conventional way of removal is to slide the cover in the direction of reciprocation along the rabbets 22 and 24 a short distance to break the oil film then lift the cover straight up. In some cases there are stop blocks attached to the surface 30 that interact with the tooling assemblies to perform certain functions. These stop blocks may limit movement of the cover so that it is difficult to break the oil film. Due to the weight of the cover, about 65 pounds, and the close fit between the flanges 26, 28 and the rabbets 22, 24, it is very difficult to reassemble the cover 18 to the tooling assembly. A guiding mechanism would be expensive to make since there is only about 0.0001 inch clearance between the parts. What is needed is a cover plate that is easily removed and reassembled and yet that is very precisely aligned with the tooling assembly when attached thereto.